Emily Davison, left, and jockey Herbert Jones fall to the ground after her collision with the King's horse, Anmer. Photograph: Hulton Archive

As an emblem of women's emancipation Emily Wilding Davison has always been controversial. The suffragette who was fatally injured at the Epsom racecourse during the Derby 100 years ago under the hooves of the king's horse has been saluted by some as a brave martyr and attacked by others as an irresponsible anarchist. Now detailed analysis of film footage of the incident has shed new light on the contentious moments on 4 June 1913 that were to go down in the history of political protest.

Despite the fact that film technology was in its early days, the incident was captured on three newsreel cameras and a new study of the images has shown that the 40-year-old campaigner was not, as assumed, attempting to pull down Anmer, the royal racehorse, but in fact reaching up to attach a scarf to its bridle.

The analysis, carried out by a team of investigators for a television documentary to be screened tonight on Channel 4, also indicates that the position of Davison before she stepped out on to the track would have given her a clear view of the oncoming race, contrary to the argument that she ran out recklessly to kill herself.

Presenter Clare Balding and investigators Stephen Cole and Mike Dixon returned to the original nitrate film stocks taken on the day and transferred them to a digital format. This was done so that they could be cleaned and so that new software could cross-reference the three different camera angles.

"It has been such an extraordinary adventure to discover more about her, about what she stood for, about the suffragette movement," said Balding this weekend on her work with the team making Secrets of a Suffragette.

"It is hugely significant as a moment in history, a moment that absolutely sums up the desperation of women in this country who wanted the vote."

Historians have suggested that Davison was trying to attach a flag to King George V's horse and police reports suggested two flags were found on her body. Some witnesses believed she was trying to cross the track, thinking the horses had passed by, others believed she had tried to pull down Anmer. The fact that she was carrying a return train ticket from Epsom and had holiday plans with her sister in the near future have also caused some historians to claim that she had no intention of killing herself.

In 2011 the horse-racing historian Michael Tanner argued that as Davison was standing in crowds on the inside of the bend at Tattenham Corner it would have been impossible for her to see the king's horse.

But new cross-referencing between the cameras has revealed, say the C4 programme makers, that Davison was closer to the start of Tattenham Corner than thought and so had a better line of sight. In this position she could have seen and singled out Anmer.

Historians have suggested that Davison and other suffragettes were seen "practising" at grabbing horses in the park near her mother's house and that they then drew lots to determine who should go to the Derby.

After colliding with Anmer, Davison collapsed unconscious on the track. The horse went over, but then rose, completing the race without a jockey. Davison died of her injuries four days later in Epsom Cottage Hospital.

At the funeral of the leading suffragette Emmeline Pankhurst in 1928, the jockey who had ridden Anmer that day, Herbert Jones, laid a wreath "to do honour to the memory of Mrs Pankhurst and Miss Emily Davison". Jones had suffered a mild concussion in the 1913 collision, but afterwards claimed he was "haunted by that poor woman's face".

In 1951, his son found Jones dead in a gas-filled kitchen. The jockey had killed himself.